Evidence of Evolution Grade 10 Biology Spring 2011

 Describe how the fossil record supports evolution  Summarize how biological molecules such as proteins and DNA are used as evidence of evolution  Infer how comparing the anatomy and development of living species provides evidence of evolution

 Fossils show a pattern of development from early ancestors to modern descendents  Offer direct evidence that evolution has taken place  Provide an actual record of Earth’s life forms  Change over time (evolution) can be seen in the fossil record

 Fossil intermediates linking great groups of organisms have been found  Between fish and amphibians  Between reptiles and birds  Between reptiles and mammals

 Based on a large body of supporting evidence, three major points:  Earth is about 4.5 billion years old  Organisms have inhabited Earth for most of its history  All organisms living today share common ancestry with earlier, simpler life forms

 The fossil record, the record of evolution of life, if not complete  Many species have lived in environments where fossils do not form  Most fossils form when organisms and traces of organisms are rapidly buried in fine sediments deposited by water, wind, or volcanic eruptions  Organisms also decay at different rates

 The fossil record will never be complete, but it still presents strong evidence to support evolution  Paleontologist: scientists who study fossils  Discover fossils and analyze sediments around it  Radiometric dating of rocks and minerals, can arrange the fossils in order from oldest to youngest  Shows orderly pattern of evolution

 Comparisons of anatomy of different types of organisms often reveal basic similarities in body structures even though the structure’s function may be different

 Vestigial structures: bones that are present in an organism but have been reduced in size and either have no use or have a less important function than they do in the other related organism  Ex. Hind limbs of whales

 Homologous Structures: are structures that share a common ancestry  As different groups of vertebrates evolved, bodies evolved differently  Similarities in bone structure can still be seen  Similar structure in two organisms can be found in the common ancestor

 Development of embryos shows evolutionary history  In some point of development all vertebrate embryos have a tail, buds that become limbs, and pharyngeal pouches

 If species have changed over time, then the genes that determine species’ characteristics should also have changed by mutation and selection  Changes would have become part of their genetic instructions  Changes in a gene’s nucleotide sequence should build up over time

 Prediction was first tested by analyzing amino acid sequence of similar proteins found in several species  Of evolution occurred, then species descended from a recent common ancestor should have fewer amino acid differences between their proteins than do species that share a common ancestor in more distant path  i.e. humans and chimps should have fewer differences in their proteins than humans and frogs

 Species that are thought to have shared a common ancestor more recently (humans and gorillas) have few amino acid sequence differences  Species that are though to have shared a common ancestor more distant past (humans and mice) have many amino acid sequence differences Hemoglobin Comparison SpeciesA.A differences from human hemoglobin protein Gorilla1 Mouse8 Rhesus monkey27 Chicken45 Frog67 Lamprey125

 This pattern, doesn’t hold true for all proteins, some proteins may evolve more rapidly than others  Evolutionary histories are generally not inferred from any single protein’s amino acid sequences  More accurate evolutionary histories are based on large numbers of gene sequences

 These evolutionary histories based on DNA sequences tend to be very similar to evolutionary histories inferred by biologist based comparative anatomy and evidence from fossil record

 Game:  olution+Review+Game.pdf olution+Review+Game.pdf